1. Field of the Invention
The present invention relates generally to communication systems, and more particularly to signal cancellation/separation architectures for use in multi-signal communication environments.
2. Background Art
A multitude of communication scenarios exist where multi-signal transmission/reception on a single frequency is needed. For example, it is desirable in duplex satellite communication systems that two or more terrestrial users use a single uplink frequency and a single downlink frequency to simultaneously communicate with a satellite transponder.
Conventional signal cancellation/separation techniques require substantial information about the signals being transmitted. For example, certain techniques require that a first signal in a composite signal is received and determined at the receiver before other signals are imposed on it. Other techniques require knowledge of several signal parameters, including amplitude, phase, frequency, spreading codes, and training sequences. Other research efforts focus on multi-path channel environments and exploit certain characteristics of these environments to remove interference from a composite signal.
Accordingly, conventional signal cancellation/separation techniques are limited to specific scenarios and are therefore not suitable to provide a general solution for this problem.
What are needed therefore are methods and systems of signal cancellation/separation that require minimal information about the transmitted signals in a composite signal and that operate in both multi-path and line-of-sight channel environments.